A112827 Least value k which is the beginning of a null Goldbach chain of length exactly n..

60, 184, 242, 114, 2314, 1382

Offset

1,1

Comments

The first even number of A112826(k/2) consisting of a run of n zeros long.

Links

Table of n, a(n) for n=1..6.

Example

a(1)=60; a(2)=184 because A112825(92) and A112825(93)=0 but A112825(91) and A112825(94) are not equal to 0.
a(3)=242 because A112825(121), A112825(122) and A112825(123)=0 but A112825(120) and A112825(124) are not equal to 0.

Mathematica

f[n_] := Block[{p = 2, q = n/2}, While[ !PrimeQ[p] || !PrimeQ[n - p], p++ ]; While[ !PrimeQ[q] || !PrimeQ[n - q], q-- ]; q - p]; t = Table[0, {10000}]; Do[a = f[2n]; If[a < 10000 && t[[a + 1]] == 0, t[[a + 1]] = 2n], {n, 2, 10^6}]; g = Flatten[ Position[t, 0]];

Crossrefs

Cf. A020481.

Sequence in context: A259946 A249911 A292223 * A181333 A082529 A126248

Adjacent sequences: A112824 A112825 A112826 * A112828 A112829 A112830

Keyword

more,nonn

Author

Robert G. Wilson v, Sep 05 2005

Status

approved